VCS::Rcs::Deltatext, simply applies 'diff -n' style patches. This format is used in RCS files to keep the file history. Because there is no other use for today (as far as I know) this class is put under VCS::Rcs::. Unless you have a verygood reason not to use patch(1)

Patch the latest revision stored in the object. $ref_deltatext is a referanse to a scalar containing the text with the diff -n style format. It is constracted from two simple command. d delete and a add. Here is a sample:

d2 1
a2 1
Text to be added
d5 4
a8 2
More text to add
And more.

This kind of format is used in RCS files. And also if you use diff(1) command with the option -n you should get the same sort of format.